Search

Zeaxanthin, a vital dietary carotenoid, is naturally synthesized by plants, microalgae, and certain microorganisms. Large-scale zeaxanthin production can be achieved through plant extraction, chemical synthesis, or microbial fermentation. The environmental and health implications of the first two methods have made microbial fermentation an appealing alternative for natural zeaxanthin production despite the challenges in scaling up the bioprocess. An intermediate between β-carotene and zeaxanthin, β-cryptoxanthin, is found only in specific fruits and vegetables and has several important functions for human health. The low concentration of β-cryptoxanthin in these sources results in low extraction yields, making biotechnological production a promising alternative for achieving higher yields. Currently, there is no industrially relevant microbial fermentation process for β-cryptoxanthin production, primarily due to the lack of identified enzymes that specifically convert β-carotene to β-cryptoxanthin without further conversion to zeaxanthin. In this study, we used genetic engineering to leverage the oleaginous yeast Yarrowia lipolytica as a bio-factory for zeaxanthin and β-cryptoxanthin production. We screened 22 β-carotene hydroxylases and identified eight novel enzymes with β-carotene hydroxylating activity: six producing zeaxanthin and two producing only β-cryptoxanthin. By introducing the β-carotene hydroxylase from the bacterium Chondromyces crocatus (CcBCH), a β-cryptoxanthin titer of 24 ± 6 mg/L was achieved, representing the highest reported titer of sole β-cryptoxanthin in Y. lipolytica to date. By targeting zeaxanthin-producing β-carotene hydroxylase to the endoplasmic reticulum and peroxisomes, we increased the production of zeaxanthin by 54% and 66%, respectively, compared to untargeted enzyme. The highest zeaxanthin titer of 412 ± 34 mg/L was achieved by targeting β-carotene hydroxylases to peroxisomes. In addition, by constructing multienzyme scaffold-free complexes with short peptide tags RIDD and RIAD, we observed a 39% increase in the zeaxanthin titer and a 28% increase in the conversion rate compared to the strain expressing unmodified enzyme. The zeaxanthin titers obtained in this study are not the highest reported; however, our goal was to demonstrate that specific approaches can enhance both titer and conversion rate, rather than to achieve the maximum titer. These findings underscore the potential of Y. lipolytica as a promising platform for carotenoid production and provide a foundation for future research, where further optimization is required to maximize production. [ABSTRACT FROM AUTHOR]

Given the necessity for bioprocesses scaling-up, the present study aims to explore the potential of three marine cyanobacteria and a consortium, cultivated in semi-continuous mode, as a green approach for i) continuous exopolysaccharide-rich biomass production and ii) removal of positively charged metals (Cu, Ni, Zn) from mono and multi-metallic solutions. To ensure the effectiveness of both cellular and released exopolysaccharides, weekly harvested whole cultures were confined in dialysis tubings. The results revealed that all the tested cyanobacteria have a stronger affinity towards Cu in mono and three-metal systems. Despite the amount of metals removed per gram of biomass decreased with higher biosorbent dosage, the more soluble carbohydrates were produced, the greater was the metal uptake, underscoring the pivotal role of released exopolysaccharides in metal biosorption. According to this, Dactylococcopsis salina 16Som2 showed the highest carbohydrate productivity (142 mg L−1 d−1) and metal uptake (84 mg Cu g−1 biomass) representing a promising candidate for further studies. The semi-continuous cultivation of marine cyanobacteria here reported assures a schedulable production of exopolysaccharide-rich biosorbents with high metal removal and recovery potential, even from multi-metallic solutions, as a step forward in the industrial application of cyanobacteria. [Display omitted] • Semi-continuous cultivation ensures consistent, schedulable biosorbent production. • Marine cyanobacteria show higher affinity to Cu than Ni and Zn dissolved in water. • Up to 84 mg Cu per gram of dry weight were removed by D. salina 16Som2. • The presence of soluble EPS improves metal uptake. [ABSTRACT FROM AUTHOR]

Dunaliella functions as a microscopic bioindustry that can capture atmospheric carbon dioxide and amass it into a range of economically viable compounds. Dunaliella‐based biorefineries have emerged as sustainable platforms for fostering a green economy and reducing carbon emissions. Dunaliella‐derived value‐added compounds are commercially important due to their application in the food, pharmaceutical, cosmeceutical, and nutraceutical sectors. The present study highlights the economic application of different Dunaliella species and the available sustainable technologies for the cultivation, harvesting, and extraction of bioactive compounds that have the potential for commercial scaleup. Their incorporation into biorefinery processes can reduce dependency on energy‐intensive and low‐yield processes. This review briefly discusses the technoeconomic analysis (TEA) of Dunaliella‐driven industrial approaches for the optimization of effective yield and determination of final production costs. The major algal biorefineries are operational in countries like Australia, China, India, Israel, Japan, Portugal, Spain and the USA. The authors have comprehensively deliberated different aspects of Dunaliella from physiological to industrial applications, meanwhile underscoring the existing knowledge gaps that impede the success of Dunaliella biorefineries. The current industrial methods being employed for biorefineries are limited to producing individual bioproducts, which may not be fully cost effective, making them less competitive in the global market. However, the analysis carried out can serve as a starting point and can guide stakeholders towards the future direction of Dunaliella‐based research and the circular bioeconomy. [ABSTRACT FROM AUTHOR]

This research aimed to model and optimize the growth factors and enhance the lipid yield from Botryococcus braunii microalgae, and to design a system for obtaining biodiesel from these lipids as this does not compromise food security. Botryococcus braunii, grown on a modified Chu‐13 medium, reached the stationary phase after 27 days with a maximum cell count of 265 × 104 cells mL−1 after 27 days and maximum biomass yield of 725 mg L−1 after 30 days on modified Chu‐13 medium, which was higher than growth on Basal SAG medium. The maximum lipid content (18.47%) and lipid yield (4.46 mg L−1day) were obtained when B. braunii was cultivated on modified Chu‐13 medium after 30 days. Gas chromatography (GC) analysis for the lipids indicated that the highest percentages of SFAs (51.03%) and lowest percentages of monounsaturated fatty acids (MUFAs) (36.47%) and polyunsaturated fatty acids (PUFAs) (12.49%) were obtained by culturing B. braunii on modified Chu‐13 medium. The effect of different growth parameters (N2 level, NaHCO3, and CO2 concentrations) on growth yield was modeled by using D‐optimal design response surface methodology (RSM). [ABSTRACT FROM AUTHOR]

Microalgae are a source of a wide variety of commodities, including particularly valuable pigments. The typical pigments present in microalgae are the chlorophylls, carotenoids, and phycobiliproteins. However, other types of pigments, of the family of water-soluble polyphenols, usually encountered in terrestrial plants, have been recently reported in microalgae. Among such microalgal polyphenols, many flavonoids have a yellowish hue, and are used as natural textile dyes. Besides being used as natural colorants, for example in the food or cosmetic industry, microalgal pigments also possess many bioactive properties, making them functional as nutraceutical or pharmaceutical agents. Each type of pigment, with its own chemical structure, fulfills particular biological functions. Considering both eukaryotes and prokaryotes, some species within the four most promising microalgae groups (Cyanobacteria, Rhodophyta, Chlorophyta and Heterokontophyta) are distinguished by their high contents of specific added-value pigments. To further enhance microalgae pigment contents during autotrophic cultivation, a review is made of the main related strategies adopted during the last decade, including light adjustments (quantity and quality, and the duration of the photoperiod cycle), and regard to mineral medium characteristics (salinity, nutrients concentrations, presence of inductive chemicals). In contrast to what is usually observed for growth-related pigments, accumulation of non-photosynthetic pigments (polyphenols and secondary carotenoids) requires particularly stressful conditions. Finally, pigment enrichment is also made possible with two new cutting-edge technologies, via the application of metallic nanoparticles or magnetic fields. [ABSTRACT FROM AUTHOR]

This study was conducted to evaluate the effects of different concentrations of two Polycyclic Aromatic Hydrocarbons (PAHs) on the profiles of soluble proteins and fatty acids and on LacsA (long-chain acyl-CoA synthesis) gene expression in Dunaliella tertiolecta and Dunaliella salina. The algae were treated with a control and three experimental concentrations (3000, 6000 and 9000 μg l‒1) of phenanthrene and anthracene. In D. salina treated with 6000 and 9000 μg l‒1 of anthracene, expression of LacsA and α-linolenic acid was higher than in the control treatment. Also, at 3000 and 6000 μg l‒1 of anthracene, there was a sharp increase in hexadecenoic acid and docosahexaenoic acid (omega-3). Dunaliella tertiolecta treated with 9000 μg l‒1of anthracene showed a stronger protein expression profile than other samples which was consistent with LacsA gene expression at the same dose of anthracene. In D. tertiolecta, α-linolenic acid and 11-octadecenoic acid increased significantly at 9000 µg l‒1 of anthracene compared to the control, and there were similar trends in proteins, LacsA gene expression and α-linolenic acid and 11-octadecenoic fatty acids content. Phenanthrene and anthracene have different molecular structures, and it seems that they also have different dose-dependent effects on synthesis/accumulation of fatty acids, SDS-PAGE profiles of proteins and LacsA gene expression in D. salina and D. tertiolecta. According to previous reports, the LacsA gene is mediated by α-linolenic acid, hexadecenoic acid and docosahexaenoic acid (omega-3) synthesis. Since PAHs tend to be accumulated in the cell membrane of the microalgae, microalgae produce various proteins and fatty acids to bioremediate these harmful substances. Our results indicated that Dunaliella spp. may be good candidates for biodegradation purposes as well as an adequate model as a biotechnological accumulator of fatty acids under exposure to PAHs.

Edible algae are a natural source of nutrients, including iodine, and can also contain nitrogen in the form of nitrate (NO3−) and nitrite (NO2−) as they can fix nitrogen from seawater. This study aimed to analyse the NO3−, NO2−, and iodine concentrations in eighteen macroalgae and five microalgae species commercially available in the United Kingdom. NO3− and NO2− concentrations were measured using high-performance liquid chromatography (HPLC), and iodine was determined using inductively coupled plasma mass spectrometry (ICP-MS). NO3− and iodine concentrations in macroalgae (NO3−: 4050.13 ± 1925.01 mg/kg; iodine: 1925.01 ± 1455.80 mg/kg) were significantly higher than in microalgae species (NO3−: 55.73 ± 93.69 mg/kg; iodine: 17.61 ± 34.87 mg/kg; p < 0.001 for both). In the macroalgae group, nori had the highest NO3− (17,191.33 ± 980.89 mg/kg) and NO2− (3.64 ± 2.38 mg/kg) content, as well as the highest iodine content. Among microalgae, Dunaliella salina had the highest concentration of NO3− (223.00 ± 21.93 mg/kg) and iodine (79.97 ± 0.76 mg/kg), while Spirulina had the highest concentration of NO2− (7.02 ± 0.13 mg/kg). These results indicate that commercially available edible algae, particularly macroalgae species, could be a relevant dietary source of NO3− and iodine. [ABSTRACT FROM AUTHOR]

The complete genome sequence of a new strain of the haloarchaeaon Halorubrum distributum ICIS4 was revealed and analyzed. The strain was isolated from a culture of a carotenogenic microalga Dunaliella salina maintained in laboratory conditions for a long period of time. The genome (3.32 Mb) contained 3236 protein-coding genes. Of the 2817 groups of homologous genes, 11 were unique to this strain. In the genome, the genes were revealed, which were responsible for utilization of glycerol and starch and for synthesis of vitamins, pigments, and siderophores. These genes may be involved in formation and maintenance of the association with microalgae. A region similar to the HRPV9 virus and another circular contig similar to a phage of the haloarchaeon Haloquadratum walsbyi were revealed in the genome assembly. [ABSTRACT FROM AUTHOR]

For the first time, the cultivated diversity of microalgae in eroded soils in the northern part of the Fergana Valley in Uzbekistan has been studied based on both morphological and molecular genetic analysis. Ten strains of green microalgae (Chlorophyta) and one charophyte strain (Charophyta) were revealed. Only seven strains could be identified at the species level: Chlorella vulgaris, Chromochloris zofingiensis, Deuterostichococcus epilithicus, Pseudomuriella schumacherensis, and Pseudostichococcus monallantoides. Another four strains were identified only at the genus level and require further study: Bracteacoccus sp., Chlorosarcinopsis sp., Klebsormidium sp., and Tetratostichococcus sp. The low species diversity in the microalgae is likely due to both the low fertility of the eroded soils on the slopes, and the limitations of the culture-based approach that only reveals a fraction of the overall microbial diversity. Microalgal colonization of eroded soils in the arid foothill zone can be facilitated by various adaptations, such as small cell size and the production of extracellular polysaccharides, mycosporine-like aminoacids, and secondary carotenoids. The present work may contribute to the further development of highly functional microalgal consortia, which can lead to improvements and sustainable development of low-productivity, arid, and degraded terrestrial ecosystems. [ABSTRACT FROM AUTHOR]

In recent years, microalgal protein (MP) has gained a lot of interest, and research on its properties and applications is steadily increasing. However, the crude protein derived from microalgae is generally undervalued and has not yet found significant applications in the food industry. There are still many issues that need to be addressed in order to promote the MP industry and make it viable. In this review, about 30 microalgal species commonly used for human consumption are depicted with their safety aspects, and the potential MP production strategies and technologies are evaluated and compared in terms of protein yield efficiency. The latest findings on the nutritional, biological, and techno-functional properties of MP are summarized to identify the potential future applications in food. Apart from that, the challenges and current issues facing the MP industry are addressed, and several technological and strategic approaches are suggested to stimulate more relevant and problem-solving research activities in this area. From the literature review, it can be concluded that MPs have balanced amino acid profiles, high quality, and good bioaccessibility. They also possess various biological activities and diverse physicochemical properties, which could be suitable for different food development needs. However, the disruption of stubborn cell walls and the migration of low sensory scores of microalgae are important challenges for the current MP industry. To increase the sustainability of MP in the human food industry, developing low-cost and large-scale microalgae cultivation strategies, seeking efficient protein purification techniques, and exploring novel applications based on the MP properties are crucial. [ABSTRACT FROM AUTHOR]

The ocean is the largest carbon reservoir on Earth and serves as a significant sink for atmospheric CO2. Of the known mechanisms for ocean CO2 absorption, the biological pump is considered the most important for carbon sequestration due to its economic and efficient advantages. Using microalgae to capture CO2 has several advantages, including a short cultivation period, high carbon sequestration efficiency, and a low investment cost. This article provides an overview of the methods used to screen algae species in microalgal carbon sequestration technology, as well as the expected effects of carbon sequestration. This article analyzes the appropriate cultivation conditions for algae, including the type of photobioreactor, light intensity, CO2 concentration, and nutritional requirements. The article contends that achieving accurate control of multiple environmental factors during microalgal cultivation and optimizing the internal structure of the cultivation device are key components for improving microalgal biomass production and CO2 fixation ability. The results of life-cycle assessments (LCA) indicate that the production of high-value compounds using microalgae is capable of achieving negative carbon emissions. Finally, this paper evaluates the practicality and economic feasibility of microalgae carbon sequestration and also discusses the future challenges and prospects for the development of this technology. [ABSTRACT FROM AUTHOR]

To achieve long-term and efficient photobiological hydrogen production by green algal aggregates remains a challenge. Herein, we demonstrated that mixotrophic cultivation of green algal aggregates can greatly increase the hydrogen production of Chlorella pyrenoidosa by 37 times, and the period of the hydrogen production was up to 21 days with a hydrogen yield of 14.97 mmol L−1. We found that glucose enabled the green algal culture flocculated by cationic etherified starch anaerobic overall, while the algal cells remained highly active. Therefore, long-term effective hydrogen production by green algae was realized. The simplicity and low cost of the method, which requires only cationic etherified starch and glucose, gives it a good potential for scale-up applications and a positive impact on the energy and environment fields. [Display omitted] • A new strategy of mixotrophic cultivation increased the H 2 production by 37 times. • H 2 production was prolonged to 21 days by supplementation with 50 mM glucose. • Large green algal aggregates up to 1000 μm were formed. • Algal aggregates were wholly anaerobic while maintaining high cellular activity. [ABSTRACT FROM AUTHOR]

AbstractMicroalgae and cyanobacteria are a rich source of carotenoids that are well known for their potent bioactivities, including antioxidant, anti-cancer, anti-proliferative, anti-inflammatory, and anti-obesity properties. Recently, many interests have also been focused on the biological activities of these microalgae/cyanobacteria-derived carotenoids, such as fucoxanthin and β-carotene potential to be the salutary nutraceuticals, on treating or preventing human common diseases (e.g., cancers). This is due to their special chemical structures that demonstrate unique bioactive functions, in which the biologically active discrepancies might attribute to the different spatial configurations of their molecules. In addition, their abundance and bioaccessibilities make them more popularly applied in food and pharmaceutical industries, as compared to the macroalgal/fungal-derived ones. This review is focused on the recent studies on the bioactivities of fucoxanthin and some carotenoids derived from microalgae and cyanobacteria in relationship with human health and diseases, with emphasis on their potential applications as natural antioxidants. Various biotechnological approaches employed to induce the production of these specific carotenoids from the culture of microalgae/cyanobacteria are also critically reviewed. These well-developed and emerging biotechnologies present promise to be applied in food and pharmaceutical industries to facilitate the efficient manufacture of the bioactive carotenoid products derived from microalgae and cyanobacteria. [ABSTRACT FROM AUTHOR]

AbstractOxygenic photosynthesis in microalgae and cyanobacteria is considered an important chassis to accelerate energy transition and mitigate global warming. Currently, cultivation systems for photosynthetic microbes for large-scale applications encountered excessive light exposure stress. High light stress can: affect photosynthetic efficiency, reduce productivity, limit cell growth, and even cause cell death. Deciphering photoprotection mechanisms and constructing high-light tolerant chassis have been recent research focuses. In this review, we first briefly introduce the self-protection mechanisms of common microalgae and cyanobacteria in response to high light stress. These mechanisms mainly include: avoiding excess light absorption, dissipating excess excitation energy, quenching excessive high-energy electrons, ROS detoxification, and PSII repair. We focus on the species-specific differences in these mechanisms as well as recent advancements. Then, we review engineering strategies for creating high-light tolerant chassis, such as: reducing the size of the light-harvesting antenna, optimizing non-photochemical quenching, optimizing photosynthetic electron transport, and enhancing PSII repair. Finally, we propose a comprehensive exploration of mechanisms: underlying identified high light tolerant chassis, identification of new genes pertinent to high light tolerance using innovative methodologies, harnessing CRISPR systems and artificial intelligence for chassis engineering modification, and introducing plant photoprotection mechanisms as future research directions. [ABSTRACT FROM AUTHOR]

Carotenoids are widely distributed and structurally diverse, which have significant roles in the photosynthesis of plants. As a precursor of vitamin A, carotenoids are also antioxidants that reduce various chronic diseases, which are beneficial for human health. Currently, the existing studies concerned the biological roles of APETALA2 (AP2)/ethylene-responsive factor (ERF) genes originated from higher plants. The AP2 superfamily of the transcriptional regulator was identified in higher plants, which was related to growth, development, carotenoid metabolism, and responses to various stresses. However, the regulatory mechanisms of the AP2-modulating carotenoid metabolism have not been reported in microalgae, which remain to be elucidated. Dunaliella parva AP2 (i.e., DpAP2), an important transcription factor, promotes carotenoid accumulation by binding to the promoter of target gene. Here, we identified an important AP2/ERF transcription factor, DpAP2, which could promote carotenoid accumulation by binding to the promoter of target gene. To demonstrate the function of DpAP2, the interacting proteins were identified by the yeast two-hybrid system. The results showed that DpAP2 could interact with three proteins with different activities (DNAbinding transcription factor activity, protein kinase activity, and alpha-Dphosphohexomutase activity); these proteins may be associated with multiple biological processes. This paper laid a good foundation for a deep understanding of the regulatory mechanisms of DpAP2 and genetic engineering breeding in D. parva. [ABSTRACT FROM AUTHOR]

AbstractThe excessive use of conventional antibiotics has resulted in significant aquatic pollution and a concerning surge in drug-resistant bacteria. Efforts have been consolidated to explore and develop environmentally friendly antimicrobial alternatives to mitigate the imminent threat posed by multi-resistant pathogens. Antimicrobial peptides (AMPs) have gained prominence due to their low propensity to induce bacterial resistance, attributed to their multiple mechanisms of action and synergistic effects. Microalgae, particularly cyanobacteria, have emerged as promising alternatives with antibiotic potential to address these challenges. The aim of this review is to present some AMPs extracted from microalgae, emphasizing their activity against common pathogens and elucidating their mechanisms of action, as well as their potential application in the aquaculture industry. Likewise, the biosynthesis, advantages and disadvantages of the use of AMPs are described. Currently, biotechnology tolls are used to enhance the action of these peptides, such as genetically modified microalgae and recombinant proteins. Cyanobacteria are also mentioned as major producers of peptides, among them, the genus Lyngbya is described as the most important producer of bioactive peptides with potential therapeutic use. The majority of cyanobacterial AMPs are of the cyclic type, meaning that they have cysteine and disulfide bridges, thanks to this, their greater antimicrobial activity and selectivity. Likewise, we found that large hydrophobic aromatic amino acid residues increase specificity, and improve antibacterial efficacy. However, based on the results of this review, it is possible to highlight that while microalgae show potential as a source of AMPs, further research in this field is necessary to achieve safe and competitive production. Therefore, the data presented here can aid in the selection of microalgal species, peptide structures, and target bacteria, with the goal of establishing biotechnological platforms for aquaculture applications. [ABSTRACT FROM AUTHOR]

Summary: The production of alkaliphilic microalgae can contribute to address the challenging cost of using pure carbon dioxide in large reactors. At high pH values, carbon dioxide is rapidly scavenged and the supply rates of dissolved inorganic carbon from the atmosphere to alkaline media are high. The present study aimed to identify microalgal strains that can cope with high alkalinity and aeration rates. Eight strains were studied and the microalgae Chlorella vulgaris, Scenedesmus almeriensis and Nannochloropsis gaditana were the only ones that were able to grow under these conditions. Their biomass productivities using laboratory‐scale bubble columns with no pH control and high aeration flow were 0.20 ± 0.03, 0.24 ± 0.03 and 0.08 ± 0.01 g·L−1·day−1, respectively. The production of the two former was scaled up to pilot‐scale bubble columns. Overall, the amount of atmospheric carbon dioxide that was transformed into biomass was in the range of 10%–30%, depending on the strain used and the photobioreactor setup. The biomass was rich in proteins and β‐carotene, both valuable products, highlighting the potential production of food ingredients while capturing carbon dioxide from the atmosphere. [ABSTRACT FROM AUTHOR]

This study was conducted to evaluate three species of Dunaliella microalgae (Dunaliella salina, Dunaliella viridis, and Dunaliella sp.) indigenous to Iran as new sources of natural chemical and bioactive compounds for exploring pharmaceutical and nutraceutical potential applications. The results showed that the fat, carbohydrate (mono‐ and di‐saccharide), dietary fiber, and protein content of Dunaliella were in the range of 13.19–25.02, 7.59–12.37, 42.10–48.82, and 17.68–22.50 (%), respectively. Dunaliella salina contained a pigment fraction of 11.50%, which was largely composed of carotenoid (7.41%) and chlorophyll (4.09%). Antioxidant capacity and inhibition of 2,2‐diphenyl‐1‐1‐picrylhydrazyl (DPPH) of Dunaliella salina were 34.54 mg/1000 g and 55.63%, respectively. The lipid profile also revealed that three isolated Dunaliella are remarkable sources of polyunsaturated fatty acids (25.42%–40.13%). Further, the ratios of ∑n‐3/∑n‐6 (2.79%), docosahexaenoic acid (6.15%), and eicosapentaenoic acid (11.26%) were the highest in Dunaliella salina. The results, thus, proved that Dunaliella spp., especially Dunaliella salina (IBRC‐M 50030), which originates from a lake in Semnan province, Iran, has potential applications in the food and pharmaceutical industries due to its appropriate biopigment, protein, lipid, antioxidant activity, long‐chain polyunsaturated fatty acids, docosahexaenoic acid, and eicosapentaenoic acid. [ABSTRACT FROM AUTHOR]

Bioactive compounds derived from microalgae have garnered considerable attention as valuable resources for drugs, functional foods, and cosmetics. Among these compounds, photosynthetic pigments and polyunsaturated fatty acids (PUFAs) have gained increasing interest due to their numerous beneficial properties, including anti-oxidant, anti-viral, anti-bacterial, anti-fungal, anti-inflammatory, and anti-tumor effects. Several microalgae species have been identified as rich sources of bioactive compounds, including the Chlorophyceae Dunaliella and Haematococcus, the Bacillariophyta Phaeodactylum and Nitzschia, and the dinoflagellate Crypthecodinium cohnii. However, most of the reported microalgae species primarily grow through autotrophic mechanisms, resulting in low yields and high production costs of bioactive compounds. Consequently, the utilization of heterotrophic microalgae, such as Chromochloris zofingiensis and Nitzschia laevis, has shown significant advantages in the production of astaxanthin and eicosapentaenoic acid (EPA), respectively. These heterotrophic microalgae exhibit superior capabilities in synthesizing target compounds. This comprehensive review provides a thorough examination of the heterotrophic production of bioactive compounds by microalgae. It covers key aspects, including the metabolic pathways involved, the impact of cultivation conditions, and the practical applications of these compounds. The review discusses how heterotrophic cultivation strategies can be optimized to enhance bioactive compound yields, shedding light on the potential of microalgae as a valuable resource for high-value product development. [ABSTRACT FROM AUTHOR]

This comprehensive study explores the intricate relationships between nutrient conditions and the growth patterns of Thalassiosira weissflogii and Chaetoceros calcitrans. Distinct flasks, subjected to varied nutrient compositions, were monitored for cell density and specific growth rates over a span of 168 hours. T. weissflogii exhibited distinct responses to F/2 Guillard media, with notable changes in cell density and growth rates, while C. calcitrans showcased nuanced dynamics under different nutrient conditions. The molecular confirmation, ITS gene sequence were done for the two microalgae strains that were bound to marine. High percentage similarity in the BLAST results of the microalgae sequences identified the species as Thalassiosira weissflogii (99.84%) and Chaetoceros calcitrans (99.79%). To accurately identify microalgae at the genus and species levels, a combination of the classical and genetic approaches is essential. The findings offer valuable insights into optimizing microalgae cultivation for biotechnological and environmental applications. [ABSTRACT FROM AUTHOR]

The salt-tolerant marine microalgae Dunaliella tertiolecta is reported to generate significant amounts of intracellular glycerol as an osmoprotectant under high salt conditions. This study highlights the phylogenetic distribution and comparative glycerol biosynthesis of seven new Dunaliella isolates compared to a D. tertiolecta reference strain. Phylogenetic analysis indicates that all Dunaliella isolates are newly discovered and do not relate to the D. tertiolecta reference. Several studies have identified light color and intensity and salt concentration alone as the most inducing factors impacting glycerol productivity. This study aims to optimize glycerol production by investigating these described factors singularly and in combination to improve the glycerol product titer. Glycerol production data indicate that cultivation with white light of an intensity between 500 and 2000 μmol m−2 s−1 as opposed to 100 μmol m−2 s−1 achieves higher biomass and thereby higher glycerol titers for all our tested Dunaliella strains. Moreover, applying higher light intensity in a cultivation of 1.5 M NaCl and an increase to 3 M NaCl resulted in hyperosmotic stress conditions, providing the highest glycerol titer. Under these optimal light intensity and salt conditions, the glycerol titer of D. tertiolecta could be doubled to 0.79 mg mL−1 in comparison to 100 μmol m−2 s−1 and salt stress to 2 M NaCl, and was higher compared to singularly optimized conditions. Furthermore, under the same conditions, glycerol extracts from new Dunaliella isolates did provide up to 0.94 mg mL−1. This highly pure algae-glycerol obtained under optimal production conditions can find widespread applications, e.g., in the pharmaceutical industry or the production of sustainable carbon fibers. [ABSTRACT FROM AUTHOR]

Hyper soil salinity is currently one of the major concerns for global agricultural yield as it directly hinders the qualitative and quantitative aspects of agronomic outcomes. Owing to ever-increasing food requirements and a vast proportion of saline agricultural land in the world, developing salinity-resilient crops is of utmost need. To address this issue, various approaches based on conventional breeding as well as biotechnological and omics-based strategies have been explored by researchers and plant breeders. Out of them, genetic engineering-based alterations of plant genomes via inserting/overexpressing beneficial salt-responsive genes originating from different organisms have shown great potential and thus explored heavily. Interestingly, a group of halotolerant organisms, plants, algae, fungi, and bacteria, collectively referred to as halobiome, holds advantageous physical, chemical, and molecular characteristics for survival in the hypersaline environment. These characteristics include effective distribution and compartmentalization of ions, elevated production of the osmoprotectants, improved activity of antioxidant machinery, and regulated synthesis of phytohormones. There are several genes from halobiome identified and successfully used to improve the salt tolerance level of glycophytic crops. However, the gene pool from the halobiome is far from its full-potential exploration. Besides, non-coding RNAs also present a potent resource to be utilized for enhancing the salinity tolerance in crop plants. Further, the use of priming agents and biofertilizers from the halobiome sources is also turning into an effective solution for plant growth enhancement and salinity tolerance. In the current review, we present the current status and recent developments in identifying and exploring halotolerant gene pools (coding and non-coding) from the constituent members of halobiome and their exploration in engineering salt-tolerant crops. Technological advancements and challenges for their full-potential exploration in crop improvement programs have been discussed. The review also provides futuristic insights about the unexplored organisms or genes from halobiome in developing salt resilience in crops. [ABSTRACT FROM AUTHOR]

The variety and efficiency of tools and strategies to genetically engineer microalgae have significantly increased within the last decade. Several alternative production concepts have been developed in microalgae, highlighting the industrial potential of these organisms for sustainable bioproduction. Yet, low product titers limit the economic feasibility in many cases. The 2-C-methyl-D-erythritol 4-phosphate (MEP) and the fatty acid synthesis pathway provide sufficient valuable metabolites to produce required terpenoids, carotenoids, as well as lipids and (modified) fatty acids. The ensuing aim for microalgal biotechnology is to strategically combine potent genetic engineering tools and improved cultivation strategies to achieve high product titers that enable economic viability. Microalgae are regarded as sustainable and potent chassis for biotechnology. Their capacity for efficient photosynthesis fuels dynamic growth independent from organic carbon sources and converts atmospheric CO 2 directly into various valuable hydrocarbon-based metabolites. However, approaches to gene expression and metabolic regulation have been inferior to those in more established heterotrophs (e.g., prokaryotes or yeast) since the genetic tools and insights in expression regulation have been distinctly less advanced. In recent years, however, these tools and their efficiency have dramatically improved. Various examples have demonstrated new trends in microalgal biotechnology and the potential of microalgae for the transition towards a sustainable bioeconomy. [ABSTRACT FROM AUTHOR]

Many dinoflagellate species are bioluminescent, which is one of the anti-predation mechanisms in these species. In addition, dinoflagellate species experience a wide range of salinities in the ocean. However, the effects of salinity on their bioluminescence intensity has only been investigated for one species. Here, we explored the effect of salinity on the bioluminescence intensity of the heterotrophic dinoflagellate Noctiluca scintillans NSDJ2010 feeding on the chlorophyte Dunaliella salina, the heterotrophic dinoflagellate Polykrikos kofoidii PKJH1607 feeding on the dinoflagellate Alexadrium minutum, and the autotrophic dinoflagellate Alexandrium mediterraneum AMYS1807. Moreover, to determine the cell volume and growth effects on bioluminescence intensity, the cell volume and growth rate of three bioluminescent dinoflagellates were simultaneously investigated. The mean 200-s-integrated bioluminescence intensity (BL) per cell, equivalent to the total bioluminescence, of N. scintillans, P. kofoidii, and A. mediterraneum was significantly affected by salinity and increased with increasing salinity from 10 to 40. The results of the present study suggest that the total bioluminescence of N. scintillans, P. kofoidii, and A. mediterraneum in offshore and oceanic waters is greater than that in estuarine waters. [ABSTRACT FROM AUTHOR]

Algal bioprospecting in ecosystems leads to exploring native microalgae and the competency evaluation of economically producing lipids as biofuel or nutritional applications. In this study, ten microalgae species were screened from the saline water lake. Chlorella vulgaris, Chlorella sorokiniana, Chlamydomonas raudensis, Chlamydomonas hedleyi, Dunaliella salina, Picochlorum bazangan sp. nov., Tetraselmis bazangan sp. nov., Haematococcus lacustris, Nannochloropsis oceanic, and Scenedesmus rubescens were isolated and identified using 18SrDNA and tufA markers. Biodiesel potentials were assayed by the determination of biomass productivity, biochemical components, fatty acid profile, and biodiesel properties. The results showed that the maximum biomass yield (1.22 g/L) belonged to C. vulgaris. The highest protein, carbohydrate, chlorophyll, and carotenoid content were recorded in C. vulgaris, C. raudensis, C. sorokiniana, and D. salina, respectively. N. oceanica accumulated high lipid content and omega-3 fractions (31.09%). However, C. hedleyi had the highest lipid productivity (11.64 g/L/day) compared to other microalgae. The best species for biodiesel production was C. vulgaris, with a specific growth rate of 0.36 day−1, lipid productivity of 7.45 g/L/day, and C16-C18 fatty acid profile of 78.3%. The microalgae C. vulgaris had appropriate biodiesel properties of low viscosity (4.49), high cetane number (55.38), and relatively low cloud point (4.98). Another choice was N. oceanic, with high lipid productivity, cetane number (59.79), oxidative stability (56.43), and low iodine value (47.11). Microalgae T. bazangan sp. nov. had a cetane number (55.24), low cloud point (4.71), and C16-C18 fatty acid profile of 82.34%. Accordingly, C. vulgaris, T. bazangan sp. nov., and N. oceanic can be considered potential species for biodiesel. [ABSTRACT FROM AUTHOR]

Ocean pollution by microplastics represents a threat to phytoplankton health, yet there is few knowledge on physical interactions between microplastics and microalgal cell surfaces. We studied the contact between environmentally aged microplastics and four microalgal species by atomic force microscopy. After seven days, microalgae showed malformations at specific sites, and these malformations varied with species. Depending on whether the cell had a porous or a smooth surface, microplastics adsorbed to the cell surface via embedding or denting, leading to minor defects or noticeable wrinkles in cell walls. Results also showed that microplastics penetrate into microalgae. Such cellular engulfment of microplastics was less present in typical diatoms because diatoms bear a porous frustule capable of trapping tiny particles. Moreover, we observed a novel type of deformation, bowl-shaped depressions, only in non-porous microalgae. The geometric features of malformations are correlated with the shape and size of microplastics. Our findings reveal for the first time the species-specific deformation in microalgae due to microplastic exposure. [ABSTRACT FROM AUTHOR]

Bioaccumulation and biomagnification of heavy metals occur constantly in the aquatic environment. Therefore, this study aimed to simulate the environment in the laboratory conditions and study the amount of lead (Pb) and cadmium (Cd) accumulation in two types of algae microalgae Dunaliella salina and Tetraselmis suecica. These algae were exposed to metals for a short duration of 21 days. After this period, they used these algae as food for Artemia salina (brine shrimp). The results showed that Pb was bio-accumulated in D. salina, between 12.65 and 1262 ppm, respectively, when exposed to a concentration of 50 and 1500 ppm., while the T. suecica was bio-accumulated Pb at a concentration of 20 and 1363 ppm when exposed to the same concentrations respectively. Also, Cd bio-accumulated in D. salina between 9.99 and 1148 ppm, while bioaccumulated Cd in T. suecica at a concentration of 10.71 and 1110.8 ppm, respectively, while when Artemia feed on algae (D. salina and T. suecica), that accumulated Pb and Cd after 21 days. The high biomagnification of Artemia for Pb (688.56 ppm) and the high bio-magnification of Artemia for Cd (700.99 ppm) when using D. salina as food. There are many environmental studies on the transfer of pollutants, especially heavy metals, in the food chain, but this study is one of the few studies that simulate the aquatic environment under controlled laboratory conditions for the accumulation of heavy metals in the food chain while minimizing the influence of interactions from other influences. [ABSTRACT FROM AUTHOR]

A taxonomic and nomenclatural account on taxa of Iridaceae proposed by Ferdinand Schur, a famous investigator of the flora of Transylvania (present‐day Romania), is presented. Types are designated for 12 names, namely lectotypes for Crocus banaticus var. niveus, C. exiguus, Iris fieberi var. monantha, I. × binata, I. × cucullata, I. pseudocyperus, I. transsilvanica, I. sibirica var. salina, and neotypes for C. banaticus var. concolor, C. banaticus var. pictus, C. banaticus var. versicolor and I. pumila var. albiflora. Based on a broad examination of Schur's original and authentic material, the taxonomic application of these names, as well as of his invalidly published and unpublished names (appearing only on herbarium labels), are clarified. It is proposed to treat I. fieberi var. monantha as a taxonomic synonym of I. aphylla, I. pumila var. albiflora and I. transsilvanica as synonyms of I. pumila, and I. sibirica var. salina as a synonym of I. spuria. The names I. × binata and I. × cucullata are accepted for the hybrids I. aphylla × pumila and I. × germanica × pallida, respectively. The treatment of I. pseudocyperus as a distinct subspecies within I. graminea is supported. All names validly published by Schur in Crocus are treated as synonyms of C. heuffelianus s.l. until an adequate taxonomic revision covering the southern Carpathian allotetraploid C. cf. heuffelianus (2n = 18) is implemented. If this polyploid deserves the rank of a distinct species, the name C. exiguus, which seems to be the earliest validly published, should be accepted for this taxon. [ABSTRACT FROM AUTHOR]

This study aimed to cultivate the microalgae Chlorella fusca LEB 111 and Spirulina sp. LEB 18 in dairy effluent supplemented with L-tryptophan to produce agricultural biostimulants rich in indoleacetic acid. After microalgae cultivation, treatments were performed on tomato seeds using biomass extracts or supernatant of cultures. The results indicated the potential of L-tryptophan supplementation in cultivating C. fusca and Spirulina in dairy effluent for an increase of 44.5% and 135.1% of the indoleacetic acid concentration. The treatments carried out on tomato seeds using biomass extracts or supernatant from microalgae cultures resulted in germination parameters of tomato seeds superior to the control treatment (distilled water), obtaining up to 100% of seed germination from the supernatant of the cultivation of C. fusca with 100% dairy effluent supplemented with L-tryptophan and from the use of biomass extract from the Spirulina cultivation condition with 25% dairy effluent supplemented with L-tryptophan, confirming the potential of using microalgae for this purpose. [ABSTRACT FROM AUTHOR]

Algae are a booming resource in the food industry due to their several health benefits. This study assesses the impact of the combined use of selected macro- and microalgae to improve the nutritional profile and the labeling of a vegetable cream by the introduction of nutrition and health claims. As macroalgae, two Ascophyllum nodosum L., one natural (An) and one smoked (AnS), were selected for their high iodine concentration and flavor notes. A new strain of Chlorella vulgaris, golden (CvG), was selected as the microalgae, which is rich in proteins and has a neutral sensorial profile (golden color and mild flavor). In this study, two vegetable creams were compared. The control (CTRL) versus one enriched with a mixture of macroalgae and microalgae (CV-AN). Sensory, physicochemical, and functional properties of both vegetable creams were evaluated. The bioactivity assessed was the effect of iodine as a health claim and antioxidant and antihypertensive properties. CV-AN vegetable cream showed significantly higher values (p < 0.05) for protein content, iodine value, and antioxidant activity, with no significant differences (p > 0.05) in antihypertensive activity or sensory panel. The incorporation of these algae resulted in a vegetable cream with a better nutritional profile and sensory acceptability comparable to the control, offering protein and iodine source claims in the labeling. [ABSTRACT FROM AUTHOR]

Bioencrustation is a natural process resulting from the colonisation and growth of organisms on solid substrates. For more than 40 years, Tributyltin (TBT) has been used as a biocide in antifouling paint. Since microalgae are constantly exposed to TBT, the growth of two microalgae species of the Guanabara Bay (Tetraselmis sp. and Chattonella subsalsa) was analysed in the present study. For this, the microalgae were grown using f/2 medium; potassium dichromate was used to guarantee the validity of the used method. To assess the effects on both genera of microalgae, different concentrations of TBT (ranging from 0.1 to 50 ng.L−1 diluted in f/2 medium) were used. All tests were carried out under a germination chamber, and the cell density was measured after 96 h. The results indicated that concentrations below 4.2 ng.L−1 were sufficient to inhibit 50% of the microalgae growth, demonstrating TBT can still be toxic even in ultra-low concentrations. [ABSTRACT FROM AUTHOR]

In order to screen out the feeding ratio of high‐quality algae strains in Hyriopsis cumingii, this experiment investigated the effects of different ratio of mixed feeding of two algae strains (Scenedesmus dimorphus and Cyclotella sp.) on the growth, bead production performance, trace elements, and amino acid composition of the newborn shell of H. cumingii. The results showed that the mixed feeding of two types of microalgae with different densities had significant effects on the growth performance, bead production quality, trace elements, and amino acid composition of the newly formed shell of H. cumingii (p < 0.05); the best body weight gain rate and shell growth rate were obtained by feeding S. dimorphus (30 × 105 cell/mL) and Cyclopella sp.(8 × 105 cell/mL); the pearl weight gain rate, amino acid ratio, Ca2+ and Mn2+ content were best when feeding Cyclotella sp. (16 × 105 cell/mL), but there was no significant difference compared with S. dimorphus (30 × 105 cell/mL) and Cyclopella sp.(8 × 105 cell/mL). In summary, the optimal feeding amount for the intensive breeding process of H. cumingii is S. dimorphus (30 × 105 cell/mL) and Cyclopella sp. (8 × 105 cell/mL). [ABSTRACT FROM AUTHOR]

Freshwater mussels (Mollusca: Unionidae) play a crucial role in freshwater river environments where they live in multi-species aggregations and often serve as long-lived benthic ecosystem engineers. Many of these species are imperiled and it is imperative that we understand their basic needs to aid in the reestablishment and maintenance of mussel beds in rivers. In an effort to expand our knowledge of the diet of these organisms, five species of mussel were introduced into enclosed systems in two experiments. In the first, mussels were incubated in water from the Clinch River (Virginia, USA) and in the second, water from a manmade pond at the Commonwealth of Virginia's Aquatic Wildlife Conservation Center in Marion, VA. Quantitative PCR and eDNA metabarcoding were used to determine which planktonic microbes were present before and after the introduction of mussels into each experimental system. It was found that all five species preferentially consumed microeukaryotes over bacteria. Most microeukaryotic taxa, including Stramenopiles and Chlorophytes were quickly consumed by all five mussel species. We also found that they consumed fungi but not as quickly as the microalgae, and that one species of mussel, Ortmanniana pectorosa, consumed bacteria but only after preferred food sources were depleted. Our results provide evidence that siphon feeding Unionid mussels can select preferred microbes from mixed plankton, and mussel species exhibit dietary niche differentiation. [ABSTRACT FROM AUTHOR]

With the increasing rate of the antimicrobial resistance phenomenon, natural products gain our attention as potential drug candidates. Apart from being used as nutraceuticals and for biotechnological purposes, microalgae and phytoplankton have well-recognized antimicrobial compounds and proved anti-infectious potential. In this review, we comprehensively outline the antimicrobial activity of one genus of cyanobacteria (Arthrospira, formerly Spirulina) and of eukaryotic microalgae (Dunaliella). Both, especially Arthrospira, are mostly used as nutraceuticals and as a source of antioxidants for health supplements, cancer therapy and cosmetics. Their diverse bioactive compounds provide other bioactivities and potential for various medical applications. Their antibacterial and antifungal activity vary in a broad range and are strain specific. There are strains of Arthrospira platensis with very potent activity and minimum inhibitory concentrations (MICs) as low as 2–15 µg/mL against bacterial fish pathogens including Bacillus and Vibrio spp. Arthrospira sp. has demonstrated an inhibition zone (IZ) of 50 mm against Staphylococcus aureus. Remarkable is the substantial amount of in vivo studies of Arthrospira showing it to be very promising for preventing vibriosis in shrimp and Helicobacter pylori infection and for wound healing. The innovative laser irradiation of the chlorophyll it releases can cause photodynamic destruction of bacteria. Dunaliella salina has exhibited MIC values lower than 300 µg/mL and an IZ value of 25.4 mm on different bacteria, while Dunaliella tertiolecta has demonstrated MIC values of 25 and 50 μg/mL against some Staphylococcus spp. These values fulfill the criteria for significant antimicrobial activity and sometimes are comparable or exceed the activity of the control antibiotics. The bioactive compounds which are responsible for that action are fatty acids including PUFAs, polysaccharides, glycosides, peptides, neophytadiene, etc. Cyanobacteria, such as Arthrospira, also particularly have antimicrobial flavonoids, terpenes, alkaloids, saponins, quinones and some unique-to-them compounds, such as phycobiliproteins, polyhydroxybutyrate, the peptide microcystin, etc. These metabolites can be optimized by using stress factors in a two-step process of fermentation in closed photobioreactors (PBRs). [ABSTRACT FROM AUTHOR]

Cobalt pollution is harmful to both the aquatic ecosystem and human health. As the primary producer of aquatic ecosystems in hypersaline environments, unicellular planktonic Dunaliella microalgae is considered to be a low-energy and eco-friendly biosorbent that removes excess cobalt and enhances the vitality of coastal and marine ecosystems. In this study, we found that the halotolerant microalga named Dunaliella sp. FACHB-558 could grow under a salinity condition with 0.5-4.5M NaCl. A phylogenetic analysis based on the rbcL gene revealed that Dunaliella sp. FACHB-558 is a close relative of Dunaliella primolecta TS-3. At labscale culture, Dunaliella sp. FACHB-558 exhibited high tolerance to heavy metal stresses, including cobalt, nickel, and cadmium. Treatment with 60 μM cobalt delayed its stationary phase but ultimately led to a higher population density. Furthermore, Dunaliella sp. FACHB-558 has the ability to adsorb the cobalt ions in the aquatic environment, which was evidenced by the decreased amount of cobalt in the culture medium. In addition, the tolerance of Dunaliella sp. FACHB-558 to cobalt stress was correlated with enhanced nitric oxide content and peroxidase activity. The autophagy inhibitor 3-MA enhanced nitric oxide burst, increased peroxidase activity, and accelerated the bioremoval of cobalt, suggesting that the autophagy pathway played a negative role in response to cobalt stress in Dunaliella sp. FACHB-558. In summary, our study identified a novel microalga possessing high cobalt tolerance and provided a promising natural biosorbent for the research and application of heavy metal bioremediation technology. [ABSTRACT FROM AUTHOR]

Non-spherical flagellate algae play an increasingly significant role in handling problematic issues as versatile biological micro/nanorobots and resources of valuable bioproducts. However, the commensalism of flagellate algae with distinct structures and constituents causes considerable difficulties in their further biological utilization. Therefore, it is imperative to develop a novel method to realize high-efficiency selection of non-spherical flagellate algae in a non-invasive manner. Enthused by these, we proposed a novel method to accomplish the selection of flagellate algae based on the numerical and experimental investigation of dielectrophoretic characterizations of flagellate algae. Firstly, an arbitrary Lagrangian--Eulerian method was utilized to study the electro-orientation and dielectrophoretic assembly process of spindle-shaped and ellipsoid-shaped cells in a uniform electric field. Secondly, we studied the equilibrium state of spherical, ellipsoid-shaped, and spindle-shaped cells under positive DEP forces actuated by rightangle bipolar electrodes. Thirdly, we investigated the dielectrophoretic assembly and escape processes of the non-spherical flagellate algae in continuous flow to explore their influences on the selection. Fourthly, freshwater flagellate algae (Euglena, H. pluvialis, and C. reinhardtii) and marine ones (Euglena, Dunaliella salina, and Platymonas) were separated to validate the feasibility and adaptability of this method. Finally, this approach was engineered in the selection of Euglena cells with high viability and motility. This method presents immense prospects in the selection of pure non-spherical flagellate algae with high motility for chronic wound healing, bio-micromotor construction, and decontamination with advantages of no sheath, strong reliability, and shape-insensitivity. [ABSTRACT FROM AUTHOR]

For plant growth under salt stress, sensing and transducing salt signals are central to cellular Na+ homoeostasis. The calcineurin B‐like protein (CBL)‐CBL‐interacting protein kinase (CIPK) complexes play critical roles in transducing salt signals in plants. Here, we show that CBL5, an ortholog of CBL4 and CBL10 in Arabidopsis, interacts with and recruits CIPK8/CIPK24 to the plasma membrane. Yeast cells coexpressing CBL5, CIPK8/CIPK24 and SOS1 demonstrated lesser Na+ accumulation and a better growth phenotype than the untransformed or SOS1 transgenic yeast cells under salinity. Overexpression of CBL5 improved the growth of the cipk8 or cipk24 single mutant but not the cipk8 cipk24 double mutant under salt stress, suggesting that CIPK8 and CIPK24 were the downstream targets of CBL5. Interestingly, seed germination in cbl5 was severely inhibited by NaCl, which was recovered by the overexpression of CBL5. Furthermore, CBL5 was mainly expressed in the cotyledons and hypocotyls, which are essential to seed germination. Na+ efflux activity in the hypocotyls of cbl5 was reduced relative to the wild‐type under salt stress, enhancing Na+ accumulation. These findings indicate that CBL5 functions in seed germination and protects seeds and germinating seedlings from salt stress through the CBL5‐CIPK8/CIPK24‐SOS1 pathways. Summary statement: Perceiving and transducing salt signals are critical to cellular Na+ homoeostasis for plant growth under salt stress. This article finds that calcineurin B‐like (CBL5) interacts with CIPK8/CIPK24 to activate SOS1 activity. The CBL5‐CIPK8/CIPK24‐SOS1 pathways may function in transducing salt signals in seed germination in Arabidopsis. [ABSTRACT FROM AUTHOR]

Microalgal biofuel is a promising solution to replace fossil fuel as a renewable and environmental‐friendly energy source, thereby contributing to the United Nations (UN) Sustainable Development Goals (SDGs), in particular SDG‐7, or Affordable and Clean Energy. Unlike energy crops (like oil palm and sugar cane), microalgae benefit from faster growth rate, higher lipid content, smaller land area required, ability to flourish using waste or brackish water, and posing zero competition with food crops. Microalgae‐derived biofuels (like biodiesel, bioethanol, biomethane, and biohydrogen) are sustainable energy sources that can be produced using well‐developed techniques (e.g., transesterification, fermentation, anaerobic digestion, and Fisher–Tropsch process). To prevent dire climate conditions resulting from the global temperature rise of 1.5°C and resolve worldwide energy security issue, our generation will need to establish and implement renewables on a global scale. To improve the industrial production of microalgal biofuel, the efficiencies of biomass and metabolite production to post‐cultivation biofuel synthesis processes must be enhanced. For the cultivation step, there exist three key techniques that can directly change the traits, structure, and behavior of microalgal cells, and induce them to accumulate targeted metabolites rapidly and in large amounts. These techniques are genetic engineering, chemical modulation, and nanomaterial approach. Genetic engineering commonly alters the chloroplast DNA of microalgae to overexpress or down‐regulate key genes in various metabolic pathways so that the cells accumulate more lipids. Chemicals can also be used to modulate microalgal growth and lipid accumulation by inducing oxidative stress or prevent conversion of lipid molecules. Nanomaterials and nanoparticles can also enhance microalgal lipid production by microenvironmental stress induction, vitamin supplementation, and light backscattering. Therefore, in this review, the recent progress as well as the pros and cons of genetic engineering, chemical modulation, and nanomaterial approach in achieving greater biofuel production from microalgae are comprehensively examined. [ABSTRACT FROM AUTHOR]

One of the major concerns affecting the public health is microbial pathogens. Commercial antibiotics have a wide range of applications, however harmful microorganisms have increased their resistance to antibiotics, making the fight against these pathogens difficult. For many years, scientists have focused on finding natural sources with strong antimicrobial activity. At this point, microalgae cells have attracted great attention due to their biological activities including, antibacterial, antifungal, and antiviral effects. In order to discover promising strains with strong antimicrobial activity and to obtain interested components efficiently, a thorough scientific approach is needed by considering all steps of the process. This process mainly consisted of strain selection, cultivation, harvesting of biomass, extraction and purification of compounds and screening their antimicrobial properties. Using microalgal compounds against microbial pathogens is still in its early days. In this context, the present review aims to contribute existing database of antimicrobial potential of microalgae. With this aim, the impact of microalgae species and their components were investigated according to their bioactivities against bacteria, fungi, and viruses. The crucial points in this regard were emphasized and important suggestions were presented for further researches. [ABSTRACT FROM AUTHOR]

Thirty-six microalgae belonging to five taxonomic groups (Cyanobacteria, Chlorophyceae, Diatomophyceae, Euglenophyceae, and Eustigmatophyceae) were identified from six freshwater ecosystems in Morocco, two treatment stations in Etueffont landfill in France and three hot spring waters in Tunisia. Investigations on species growth kinetics and growth rates showed that the cyanobacterium Leptolyngbya gelatinosa exhibited both the highest biomass and growth rate with 4 g DW L−1 and 0.282 day−1, respectively. A significant protein production (more than 40% DW) was observed across the studied species. Cyanobacteria and chlorophytes stood out for their increased protein production with a maximum (66.63 ± 3.84% DW) attained by the cyanobacterium Leptolyngbya sp. Chlorophytes produced substantial amounts of carbohydrates (more than 20% DW). Euglenophytes including Phacus orbicularis and Euglena ehrenbergii along with the chlorophyte Graesiella sp. accumulated significant amounts of lipids (up to 31.12% DW). [ABSTRACT FROM AUTHOR]

Wadi El-Natrun is one of the most observable geomorphological features in the North-Western Desert of Egypt; it contains several old saline and saline soda lakes. This study investigates physicochemical and biochemical characteristics and estimates the total phenolic content (TPC), total flavonoid content (TVC), and bioactivities of sediment, cyanobacteria, and brine shrimp (Artemia salina) in soda lakes, i.e., El-Hamra Lake 1 (H1) and El-Hamra Lake 2 (H2). These soda lakes are unique extreme ecosystems characterized by high pH (> 9.3), high alkalinity, and salinity. Some extremophilic microorganisms are hosted in this ecosystem. The results revealed that the chemical water type of studied lakes is soda-saline lakes according to the calculated percentage sequence of major cations and anions. Sodium ranked first among major cations with an abundance ratio of e% 58, while chloride came first among anions with an abundance ratio of e% 71, and bicarbonate and carbonate occupied the last rank with an abundance of 6%. The biochemical investigations showed that TPC and TVC are present in concern contents of sediment, cyanobacteria, and brine shrimp (A. salina) which contribute 89% of antioxidant capacity and antimicrobial activities. Thus, this study helps better understand the chemical and biochemical adaptations in soda lake ecosystems and explores natural sources with potential applications in antioxidant-rich products and environmental conservation efforts. [ABSTRACT FROM AUTHOR]

The adaptive potential of plants in urban environments, responding to factors like air pollution, electromagnetic radiation, and specific microclimates, remains insufficiently understood. Our study focused on two evergreen Cupressaceae family species, Thuja occidentalis L. and Platycladus orientalis L. Franco, which are commonly found in Kazakhstan's urban landscapes. Conducted in Almaty, one of Kazakhstan's most polluted cities, our comparative analysis examined the anatomical features, photosynthetic activity, and secondary metabolite composition of these conifers. Both species exhibited xeromorphic traits, such as submerged stomata, resin passages, and a prominent leaf cuticle. T. occidentalis displayed higher photosynthetic activity values (quantum yield of photosystem II (YII), electron transport rate (ETR), and quantum yield of non-photochemical quenching (Y(NPQ))) than P. orientalis, while P. orientalis exhibited a higher quantum yield of non-regulated energy dissipation in PSII (Y(NO)) values. Chemical analysis revealed 31 components in T. occidentalis and 33 in P. orientalis, with T. occidentalis containing three times more thujone (16.42% and 5.18%, respectively) and a higher monosaccharide content (17.33% and 6.98%, respectively). T. occidentalis also contained 14.53% steroids, whereas P. orientalis showed no steroid presence. The cytotoxic activity of essential oils was determined by the survival of Artemia salina aquatic crustaceans, whereas tested essential oils from both species exhibited acute lethal toxicity to A. salina aquatic crustaceans across all tested concentrations. The connection between physiological traits, adaptation strategies, and cytotoxic effects offers a comprehensive view of the ecological and pharmacological importance of these two observed conifer species, highlighting their diverse roles in urban environments, as well as their potential medical uses. [ABSTRACT FROM AUTHOR]

Porphyridium aerugineum is a unicellular freshwater red microalga that synthesizes and secretes into the culture medium an extracellular polysaccharide (EPS). In this study, algal growth and polysaccharide production, as well as the antioxidant capacity and antitumor effect of Porphyridium aerugineum EPS (PaEPS), were investigated. Cultivation of the microalgae was carried out in a photobioreactor under controlled conditions. Algal growth and the amount of EPS were monitored daily. The accumulated polysaccharide was extracted and lyophilized. At the end of cultivation, the concentration of microalgal biomass and PaEPS reached 3.3 and 1.2 g L−1, respectively. To examine the antioxidant capacity of PaEPS, FRAP and ABTS assays were performed. The cytotoxic activity of PaEPS was evaluated on the tumor cell lines MCF-7 (breast cancer) and HeLa (cervical adenocarcinoma) and on BJ (a non-tumor human skin fibroblast cell line), using MTT assay. The results obtained indicated that P. aerugineum polysaccharide exhibited a high ABTS radical-scavenging activity reaching up to 55%. The cytotoxic effect was best expressed in MCF-7 cells treated for 72 h with 1000 µg/mL PaEPS, where tumor cell proliferation was inhibited by more than 70%. Importantly, the PaEPS treatments did not significantly affect the viability of BJ cells. These findings promote the biotechnological production of P. aerugineum extracellular polysaccharide and reveal its potential as an anticancer and antioxidant agent for future applications. [ABSTRACT FROM AUTHOR]

This study aimed to reduce the occurrence of algal blooms by decreasing nitrogen and phosphorus elution leaked from livestock manure sprayed on farmland in dams and river basins. Excessive algal growth affects water availability by disturbing the aquatic ecosystem, clogging filters of the water intake tower, generating toxins, and causing social and economic losses. Nutrients discharged from nonpoint pollution sources (farmlands and barns) often flow into rivers without being purified, thus contaminating nearby river basins. An analysis of algal growth characteristics by dividing rainfall runoff into raw solution, nitrogen and phosphorus adsorbent (NPA) compost, and general compost affected growth rate and microalgae biomass production as well as nitrogen and phosphorus removal rates. Blue-green algae (Microcystis aeruginosa) and green algae (Scenedesmus acutus) were diluted, and the effect of reduction of microalgae growth was studied in all experiments. Results of water quality analysis reveal that eco-friendly compost has the effect of reducing nutrient salts in rainfall runoff by 30%-40% compared to general compost. Furthermore, the growth of blue-green algae and green algae can be reduced if the effluent of eco-friendly compost flows into the river and the nutrient concentration is lowered. [ABSTRACT FROM AUTHOR]

The cost and efficiency of an algal-BS treatment system are determined by the specific microalgal species and BS pretreatment method. This study examines the growth of a novel algae Chlorella sp. YSD-2 and the removal of nutrients from the BS using different pretreatment methods, including dilution ratio and sterilization. The highest biomass production (1.84 g L−1) was achieved in the 1:2 unsterilized biogas slurry, which was 2.03 times higher than that in the sterilized group, as well as higher lipid productivity (17.29 mg L−1 d−1). Nevertheless, the sterilized biogas slurry at a 1:1 dilution ratio exhibited the most notable nutrient-removal efficiency, with COD at 71.97%, TP at 91.32%, and TN at 88.80%. Additionally, the analysis of 16S rRNA sequencing revealed a significant alteration in the indigenous bacterial composition of the biogas slurry by microalgal treatment, with Proteobacteria and Cyanobacteria emerging as the predominant phyla, and unidentified_Cyanobacteria as the primary genus. These findings suggest that Chlorella sp. YSD-2 exhibits favorable tolerance and nutrient-removal capabilities in unsterilized, high-strength biogas slurry, along with high productivity of biomass and lipids. Consequently, these results offer a theoretical foundation for the development of an efficient and economically viable treatment method for algal-BS. [ABSTRACT FROM AUTHOR]

There are many studies on the toxic effects of single nanoparticles on microalgae; however, many types of nanoparticles are present in the ocean, and more studies on the combined toxic effects of multiple nanoparticles on microalgae are needed. The single and combined toxic effects of nCu and nSiO2 on Dunaliella salina were investigated through changes in instantaneous fluorescence rate (Ft) and antioxidant parameters during 96-h growth inhibition tests. It was found that the toxic effect of nCu on D. salina was greater than that of nSiO2, and both showed time and were dose-dependent with the greatest growth inhibition at 96 h. A total of 0.5 mg/L nCu somewhat promoted the growth of microalgae, but 4.5 and 5.5 mg/L nCu showed negative growth effects on microalgae. The Ft of D. salina was also inhibited by increasing concentrations of nanoparticles and exposure time. nCu suppressed the synthesis of TP and elevated the MDA content of D. salina, which indicated the lipid peroxidation of algal cells. The activities of SOD and CAT showed a trend of increasing and then decreasing with the increase of nCu concentration, suggesting that the enzyme activity first increased and then decreased. The toxic effect of a high concentration of nCu was reduced after the addition of nSiO2. SEM and EDS images showed that nSiO2 could adsorb nCu in seawater. nSiO2 also adsorbed Cu2+ in the cultures, thus reducing the toxic effect of nCu on D. salina to a certain extent. TEM image was used to observe the morphology of algal cells exposed to nCu. [ABSTRACT FROM AUTHOR]